JP6505157B2 - Method of manufacturing spark plug - Google Patents

Description

  The present invention relates to the manufacture of a spark plug used for ignition in an internal combustion engine or the like.

  Patent Document 1 discloses a method of inspecting the withstand voltage performance of an insulator of a spark plug. In this inspection method, in an assembly in which the metal shell, the terminal metal, the center electrode, and the insulator are assembled, a voltage is applied between the terminal metal and the metal shell. When the insulator has a defect such as a crack, the current flows through the defect, and the voltage that can be applied is low. Therefore, when the applied voltage exceeds the predetermined value, the withstand voltage performance of the insulator is determined to be good, and when the applied voltage is equal to or less than the predetermined value, the withstand voltage performance of the insulator Is judged not to be good. Here, in this inspection method, the application of the voltage is performed in a state where the rear end portion of the insulator is covered with the insulating cylindrical insulating member. This can suppress the phenomenon in which a voltage flows between the terminal fitting and the metal shell through the vicinity of the rear end of the insulator (also referred to as the flashover phenomenon), thereby avoiding a situation where the withstand voltage performance can not be inspected.

JP, 2013-89428, A

  Here, as the insulating member is brought into close contact with the insulator, the flashover phenomenon can be suppressed. However, if the insulating member is strongly adhered to the insulator, it becomes difficult to remove the insulating member from the insulator after the inspection, which may hinder the smooth progress of the inspection.

  The present specification discloses a technology capable of smoothly advancing inspection while suppressing the flashover phenomenon at the time of inspection of an insulator of a spark plug.

The technology disclosed herein can be implemented as the following application or form .
[Form 1]
A method of manufacturing a spark plug including an insulator inspection step, comprising:
The inspection process of the insulator is
(A) A cylindrical metal shell having a through hole extending in the axial direction, and a part thereof is held in the through hole, the rear end is exposed to the rear end side from the metal shell, and extends along the axial direction An insulator having an axial hole, a center electrode whose rear end is located in the axial hole, and a front end located on the rear end side of the central electrode in the axial hole from the rear end, the rear end is more than the insulator Preparing an assembly comprising a terminal fitting exposed on the rear end side and a ground electrode joined to the metal shell;
(B) attaching the assembly to the pressure vessel such that a portion on the tip side of the assembly is located inside the pressure vessel;
(C) attaching an insulating member including a cylindrical portion to the assembly so as to cover the surface of at least a portion of the portion of the insulator exposed to the rear end side of the metal shell;
(D) pressurizing the inside of the pressure vessel and applying a predetermined voltage between the terminal fitting and the metal shell;
(E) removing the insulating member from the assembly after application of the predetermined voltage;
Equipped with
Before the step (c), at least the insulation of the surface of the insulator covered by the insulating member attached in the step (c) and the inner surface of the insulating member covering the surface of the insulator A method for manufacturing a spark plug, comprising a lubricant adhesion step of adhering lubricant to a surface of a body.
[Form 2]
A method of manufacturing a spark plug including an insulator inspection step, the method comprising:
The inspection process of the insulator is
(A) A cylindrical metal shell having a through hole extending in the axial direction, and a part thereof is held in the through hole, the rear end is exposed to the rear end side from the metal shell, and extends along the axial direction An insulator having an axial hole, a center electrode whose rear end is located in the axial hole, and a front end located on the rear end side of the central electrode in the axial hole from the rear end, the rear end is more than the insulator Preparing an assembly comprising a terminal fitting exposed on the rear end side and a ground electrode joined to the metal shell;
(B) attaching the assembly to the pressure vessel such that a portion on the tip side of the assembly is located inside the pressure vessel;
(C) attaching an insulating member including a cylindrical portion to the assembly so as to cover the surface of at least a portion of the portion of the insulator exposed to the rear end side of the metal shell;
(D) pressurizing the inside of the pressure vessel and applying a predetermined voltage between the terminal fitting and the metal shell;
(E) removing the insulating member from the assembly after application of the predetermined voltage;
Equipped with
Before the step (c), the method further comprises a lubricant adhering step of adhering a lubricant on the inner surface of the insulating member covering the surface of the insulator;
The method for manufacturing a spark plug, wherein the lubricant attachment step is a step of bringing an object to which the lubricant is attached into contact with the inner surface of the insulating member.

[Example 1 of application] A method of manufacturing an ignition plug including a step of inspecting an insulator,
The inspection process of the insulator is
(A) A cylindrical metal shell having a through hole along the axial direction, and a part thereof is held in the through hole, and a rear end is exposed to the rear end side from the metal shell, along the axial direction An insulator having an extending axial hole, a center electrode whose rear end is located in the axial hole, and a front end located on the rear end side of the central electrode in the axial hole from the rear end, the rear end is the insulator Preparing an assembly comprising a terminal fitting exposed to the rear end side and a ground electrode joined to the metal shell;
(B) attaching the assembly to the pressure vessel such that a portion on the tip side of the assembly is located inside the pressure vessel;
(C) attaching an insulating member including a cylindrical portion to the assembly so as to cover the surface of at least a portion of the portion of the insulator exposed to the rear end side of the metal shell;
(D) pressurizing the inside of the pressure vessel and applying a predetermined voltage between the terminal fitting and the metal shell;
(E) removing the insulating member from the assembly after application of the predetermined voltage;
Equipped with
Prior to the step (c), at least one of the surface of the insulator covered by the insulating member attached in the step (c) and the inner surface of the insulating member covering the surface of the insulator A method of manufacturing a spark plug, comprising a lubricant adhering step of adhering a lubricant.

  According to the above configuration, the surface of the insulator covered by the insulating member before the insulating member including the tubular portion is attached so as to cover at least a part of the surface of the portion exposed to the rear end in the insulator. , Let the lubricant adhere. As a result, even if the insulating member is strongly adhered to the insulator, it becomes easy to remove the insulating member from the assembly after application of a predetermined voltage. Therefore, during the inspection of the insulator of the spark plug, the inspection can be smoothly progressed while suppressing the flashover phenomenon along the portion exposed to the rear end side of the insulator.

Application Example 2 The method for manufacturing the spark plug according to Application Example 1 includes
The method for manufacturing a spark plug, wherein the lubricant is talc powder.

  Even if a small amount of talc powder adheres to the insulator, it hardly affects the performance and appearance of the spark plug. According to the above configuration, since talc powder is used as the lubricant, the talc powder removal process can be omitted or simplified.

Application Example 3 The method for manufacturing the spark plug according to Application Example 1 or 2 is,
The method for manufacturing a spark plug, wherein the lubricant attachment step is a step of bringing an object to which the lubricant is attached into contact with at least one of the surface of the insulator and the inner surface of the insulating member.

  According to the above configuration, the lubricant can be easily attached to the surface of the insulator.

Application Example 4 This is a method for manufacturing the spark plug according to Application Example 3, and
The method for manufacturing a spark plug, wherein the object to which the lubricant adheres is a cloth bag containing the powder of the lubricant.

  According to the above configuration, the powdery lubricant can be easily attached to the surface of the insulator.

  Note that the technology disclosed in the present specification can be realized in various aspects, and can be realized, for example, in an aspect such as a spark plug inspection device.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which cut | disconnected the spark plug of embodiment by the surface where an axis is included. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the whole structure of the test | inspection apparatus of the ignition plug of this embodiment. It is sectional drawing which cut | disconnected the press conduction part in the plane containing an axis. It is a perspective view of a pressure vessel. It is a flowchart which shows the process of the manufacturing method of a spark plug. It is explanatory drawing of the manufacturing method of a spark plug. It is an explanatory view showing an inspection device and an assembly of a state where S40 was performed. It is an explanatory view showing an inspection device and an assembly of a state where S60 is performed.

A. Embodiment:
A-1. Configuration of spark plug:
Hereinafter, embodiments of the present invention will be described based on the embodiments. FIG. 1 is a cross-sectional view of the spark plug 100 according to the embodiment cut along a plane including the axis. The dashed-dotted line in FIG. 1 indicates the axis CL1 of the spark plug 100. A direction parallel to the axis line CL1 (vertical direction in FIG. 1) is also referred to as an axial direction. The radial direction of a circle on a plane perpendicular to the axis line CL1 with the axis line CL1 as the center is also simply referred to as "radial direction", and the circumferential direction of the circle is also simply referred to as "circumferential direction". The downward direction in FIG. 1 is referred to as a front end direction FD, and the upward direction is also referred to as a back end direction BD. The lower side in FIG. 1 is called the front end side of the spark plug 100, and the upper side in FIG. 1 is called the rear end side of the spark plug 100.

  The spark plug 100 is attached to an internal combustion engine and is used to ignite combustion gases in a combustion chamber of the internal combustion engine. The spark plug 100 includes an insulator 10, a center electrode 20, a ground electrode 30, a terminal fitting 40, a metal shell 50, a resistor 70, and seal members 60 and 80.

The insulator 10 is formed using, for example, a ceramic containing Al ₂ O ₃ (alumina) as a main component. The insulator 10 is a substantially cylindrical member extending along the axial direction. The insulator 10 has an axial hole 12 which is a through hole extending along the axial direction and penetrating the insulator 10. The insulator 10 includes a collar portion 19, a rear end side body portion 18, a front end side body portion 17, a first reduced outer diameter portion 15, and a leg length portion 13. The rear end side body portion 18 is located on the rear end side of the collar portion 19 and has an outer diameter smaller than the outer diameter of the collar portion 19. The tip end side body portion 17 is positioned on the tip end side of the collar portion 19 and has an outer diameter smaller than the outer diameter of the collar portion 19. The long leg portion 13 is located on the tip end side of the tip end side body portion 17 and has an outer diameter smaller than the outer diameter of the tip end side body portion 17. The leg 13 is exposed to the combustion chamber when the spark plug 100 is attached to the internal combustion engine (not shown). The first reduced outer diameter portion 15 is formed between the leg length portion 13 and the distal end side body portion 17. The outer diameter of the first reduced outer diameter portion 15 decreases toward the tip end in the axial direction.

  The metal shell 50 is formed of a conductive metal material (for example, low carbon steel material) and is a cylindrical metal fitting for fixing the spark plug 100 to an engine head (not shown) of an internal combustion engine (FIG. 1). The metal shell 50 is formed with a through hole 59 penetrating along the axis line CL1. The metal shell 50 is disposed on the outer periphery of the insulator 10. That is, the insulator 10 is inserted and held in the through hole 59 of the metal shell 50. The end of the insulator 10 is exposed to the end side of the end of the metal shell 50. The rear end of the insulator 10 is exposed to the rear end side from the rear end of the metal shell 50.

  The metal shell 50 is formed between a tool engagement portion 51 in the shape of a hexagonal column engaged with the spark plug wrench, a mounting screw portion 52 for mounting to an internal combustion engine, the tool engagement portion 51 and the mounting screw portion 52 And a hooked seat portion 54. The nominal diameter of the mounting screw portion 52 is, for example, one of M8 (8 mm (millimeter)), M10, M12, M14, and M18.

  An annular gasket 5 formed by bending a metal plate is inserted between the mounting screw portion 52 of the metal shell 50 and the seat portion 54. The gasket 5 seals a gap between the spark plug 100 and the internal combustion engine (engine head) when the spark plug 100 is attached to the internal combustion engine.

  The metal shell 50 further includes a thin caulking portion 53 provided on the rear end side of the tool engagement portion 51, and a thin compression deformation portion 58 provided between the seat portion 54 and the tool engagement portion 51. And have. An annular region is formed in an annular region formed between the inner peripheral surface of a portion from the tool engagement portion 51 to the caulking portion 53 in the metal shell 50 and the outer peripheral surface of the rear end side body portion 18 of the insulator 10. Ring members 6, 7 are arranged. A powder of talc (talc) 9 is filled between the two ring members 6 and 7 in the area concerned. The rear end of the crimped portion 53 is bent inward in the radial direction and fixed to the outer peripheral surface of the insulator 10. The compression deformation portion 58 of the metal shell 50 is compressed and deformed when the crimped portion 53 fixed to the outer peripheral surface of the insulator 10 is pressed toward the tip end during manufacturing. By the compression deformation of the compression deformation portion 58, the insulator 10 is pressed toward the tip side in the metal shell 50 through the ring members 6, 7 and the talc 9. The first reduced outer diameter portion 15 of the insulator 10 is pressed by the shelf portion 56 formed on the inner periphery of the mounting screw portion 52 of the metal shell 50 via the metal annular plate packing 8. As a result, the plate packing 8 prevents the gas in the combustion chamber of the internal combustion engine from leaking from the gap between the metal shell 50 and the insulator 10 to the outside.

  The terminal fitting 40 is a rod-like member extending in the axial direction, and is disposed on the rear end side of the axial hole 12 of the insulator 10. The terminal fitting 40 is formed of a conductive metal material (for example, low carbon steel), and a metal layer (for example, a Ni layer) for corrosion protection is formed on the surface of the terminal fitting 40 by plating or the like. The terminal fitting 40 includes a hook 42 (terminal jaw) formed at a predetermined position in the axial direction, a cap mounting part 41 positioned on the rear end side of the hook 42, and a leg 43 on the tip end side of the hook 42 And (terminal legs). The cap mounting portion 41 of the terminal fitting 40 is exposed to the rear end side of the insulator 10. The leg portion 43 of the terminal fitting 40 is inserted into the axial hole 12 of the insulator 10. That is, the front end of the terminal fitting 40 is located on the rear end side of the center electrode 20 in the shaft hole 12 from the rear end of the center electrode 20, and the rear end is exposed on the rear end side of the insulator 10. A plug cap to which a high voltage cable (not shown) is connected is mounted on the cap mounting portion 41, and a high voltage for generating a spark discharge is applied.

  The center electrode 20 is a substantially rod-like member extending in the axial direction. The center electrode 20 is disposed on the tip end side of the axial hole 12 of the insulator 10. The rear end of the center electrode 20 is located in the shaft hole 12, and the tip of the center electrode 20 is exposed to the tip side of the insulator 10. The center electrode 20 includes a substantially rod-shaped center electrode body 25 and a column-shaped center electrode tip 29 joined to the tip of the center electrode body 25 (FIG. 1).

  The ground electrode 30 is a curved rod-like body having a square cross section. The rear end portion of the ground electrode 30 is joined to the front end surface of the metal shell 50 by welding. Thus, the metal shell 50 and the ground electrode 30 are electrically connected. The tip of the ground electrode 30 is a free end. The gap between the center electrode tip 29 and the vicinity of the free end of the ground electrode 30 is a so-called spark gap in which a spark discharge occurs. The ground electrode 30 may be provided with a ground electrode tip similar to the center electrode tip 29 in a portion where a spark gap is formed.

  The ground electrode 30 and the center electrode body 25 are formed using, for example, nickel or an alloy containing nickel as a main component (eg, NCF 600, NCF 601). The ground electrode 30 and the center electrode body 25 are formed using a base material formed of a metal (for example, nickel alloy) having high corrosion resistance and a metal (for example, copper) having a high thermal conductivity. It may have a two-layer structure including an embedded core part. The center electrode tip 29 is formed using, for example, a noble metal such as Pt (platinum) or Ir (iridium) or an alloy containing a noble metal as a main component.

  The resistor 70 is disposed in the axial hole 12 of the insulator 10 between the front end of the terminal fitting 40 (the front end of the leg portion 43) and the rear end of the center electrode 20 (the rear end of the center electrode body 25). . That is, the resistor 70 is disposed in the axial hole 12 closer to the rear end side in the axial direction than the center electrode 20. The resistor 70 has, for example, a resistance value (for example, 5 KΩ) of 1 KΩ or more, and has a function of reducing radio wave noise at the time of spark generation. The resistor 70 is formed of, for example, a composition including glass particles as main components, ceramic particles other than glass, and a conductive material.

The seal member 60 is disposed in the axial hole 12 between the resistor 70 and the center electrode 20 (center electrode body 25), and fills the gap between the resistor 70 and the center electrode 20. The seal member 80 is disposed between the resistor 70 and the terminal fitting 40 (leg portion 43) in the shaft hole 12 and fills the gap between the resistor 70 and the terminal fitting 40. The seal members 60 and 80 are formed of a conductive material, for example, a composition including glass particles such as B ₂ O ₃ —SiO ₂ and metal particles (Cu, Fe, etc.). The resistance value of the seal members 60, 80 is less than 1 KΩ, for example, several hundred mmΩ.

A-2. Method of Manufacturing Spark Plug 100 Next, a method of manufacturing the above-described spark plug 100 will be described. The method of manufacturing the spark plug 100 includes a test of the withstand voltage of the insulator 10 of the spark plug 100. In the following, the inspection of the withstand voltage of the insulator 10 will be mainly described.

A-2-1. Overall Configuration of Inspection Device for Spark Plug 100 FIG. 2 is a view showing the overall configuration of the inspection device 500 for the spark plug 100 of the present embodiment. As shown in FIG. 2, an assembly 100A, which is an intermediate product in the manufacturing process of the spark plug 100, is attached to the inspection device 500 at the time of the inspection of the voltage resistance. The assembly 100A differs from the spark plug 100 only in that the ground electrode 30 is not bent and the gasket 5 is not assembled in the assembly 100A. For this reason, the axis of the assembly 100A is the same as the axis CL1 of the spark plug 100. Here, when the assembly 100A is attached to the inspection apparatus 500, a straight line that coincides with the axis CL1 of the assembly 100A is taken as an axis CL2 of the inspection apparatus 500. Then, as in FIG. 1, in FIG. 2, the radial direction of the circle on the plane perpendicular to the axis line CL2 is simply referred to as “radial direction” with the axis line CL2 as the center, and the circumferential direction of the circle is simply Also called "direction". The downward direction in FIG. 2 (that is, the vertically downward direction of the inspection apparatus 500) is also referred to as a front end direction FD, and the upward direction in FIG. 2 (that is, the vertically upward direction of the inspection apparatus 500) is also referred to as a back end direction BD. The lower side in FIG. 2 (that is, the vertically lower side of the inspection apparatus 500) is called the tip side of the inspection apparatus 500, and the upper side in FIG. 2 (that is, the vertically upper side of the inspection apparatus 500) is the rear end side of the inspection apparatus 500. Call it

  The inspection apparatus 500 includes a pressure applying unit 200, a pressure vessel 300, a voltage applying unit 400, a lower fixing plate 410, an upper fixing plate 420, a pair of columns 430, a pair of slide supports 440, and a movable shelf And 450 are provided.

  By pressing the assembly 100A attached to the pressure vessel 300 in the front direction FD, the pressure applying unit 200 seals the opening of the sealing portion 314 (described later) of the pressure vessel 300 with the assembly 100A. In addition, the pressure applying unit 200 applies current to the assembly 100A when the withstand voltage of the insulator 10 is inspected. The pressure applying unit 200 is fixed to the surface on the tip side of the movable shelf 450. An insertion hole 290 extending in the axial direction is formed in the pressure applying portion 200 at a position intersecting the axis line CL1. When the withstand voltage test of the insulator 10 is performed, a part of the rear end side of the assembly 100A is inserted into the insertion hole 290. The pressure applying unit 200 includes a conductive pin 210 on the rear end side. The conductive pin 210 is disposed movably along the axial direction in the insertion hole 290. The detailed configuration of the pressure applying unit 200 will be described later.

  The pressure vessel 300 has a substantially cylindrical shape whose central axis extends in the axial direction, and is fixed to the surface on the rear end side of the lower fixing plate 410. Inside the pressure vessel 300, a bottomed substantially cylindrical space (hereinafter referred to as a "chamber 370") is formed. At the end on the rear end side of the chamber 370 (the upper end in FIG. 2), a sealing portion 314 having an opening at the center is disposed, and the opening of the sealing portion 314 is closed by the assembly 100A. The inside of the chamber 370 becomes airtight due to the peeling. The chamber 370 is connected to an air tank (not shown) and a pressure regulating valve, and the pressure regulating valve regulates the pressure inside the chamber 370. The inside of the chamber 370 is pressurized to a predetermined pressure (5 MPa in the present embodiment). Note that any pressure in the range of 0 MPa to 5 MPa may be employed as the predetermined pressure, instead of 5 MPa. The bottom 380 of the chamber 370 is formed of a transparent material such as acrylic resin or glass so that the inside of the chamber 370 can be viewed. Therefore, as described later, the front end of the assembly 100A located in the chamber 370 can be photographed from the rear end side of the pressure vessel 300. For this reason, the presence or absence of the defect in the insulator 10 can be easily confirmed by the captured image. The detailed configuration of the pressure vessel 300 will be described later.

  The voltage application unit 400 applies a predetermined voltage (for example, 30 to 45 kV in the present embodiment) to the assembly 100A when performing a test of withstand voltage. The voltage application unit 400 includes a conductive pin drive unit 405. The conductive pin drive unit 405 moves the conductive pin 210 in the axial direction by pressing or pulling the conductive pin 210 in the axial direction, although the detailed structure is not shown. Further, the conductive pin drive unit 405 applies a voltage so that the potential of the conductive pin 210 becomes a predetermined potential.

  The lower fixing plate 410 is a plate-like member disposed perpendicularly to the axis line CL2. In the lower fixing plate 410, a through hole 412 penetrating in the thickness direction (axial direction) is formed at a position intersecting the axis line CL2. The through hole 412 is formed at a position corresponding to the bottom 380 of the pressure vessel 300. For this reason, the inside of the chamber 370 can be viewed through the through hole 412 and the bottom portion 380 by viewing from the tip side of the lower fixing plate 410 toward the tip direction FD. An imaging device (not shown) is disposed in the through hole 412, and the tip of the assembly 100A disposed in the chamber 370 is imaged.

  The upper fixing plate 420 is a plate-like member disposed perpendicularly to the axis line CL 2, and is arranged at a rear end side of the lower fixing plate 410 so as to be separated by a predetermined distance. The pair of columns 430 is a cylindrical member extended along the axial direction, one end of which is connected to the lower fixing plate 410 and the other end of which is connected to the upper fixing plate 420. Each of the pair of slide support portions 440 has a substantially cylindrical shape. The pair of slide supports 440 are axially movably attached to the different columns 430, and move along the axial direction by a drive unit (not shown).

  The movable shelf 450 is a plate-like member disposed perpendicularly to the axis line CL 2, and both ends of the movable shelf 450 are connected to the pair of slide support portions 440 respectively. As the slide support portion 440 moves in the axial direction, the movable rack 450 moves (lifts) in the axial direction while maintaining the state perpendicular to the axis line CL2. A pressure applying unit 200 is installed on the surface on the front end side of the movable shelf 450, and a voltage application unit 400 is installed on the surface on the rear end side. In the moving shelf 450, a through hole penetrating in the thickness direction (axial direction) is formed at a position intersecting the axis CL2, and a part of the pressing / energizing unit 200 is disposed in the through hole. ing. In the present embodiment, the lower fixing plate 410, the upper fixing plate 420, the pair of columns 430, the pair of slide support portions 440, and the movable shelf 450 are all formed of steel.

A-2-2. Detailed Configuration of Pressing and Conducting Unit 200 FIG. 3 is a cross-sectional view of the pressing and conducting unit 200 shown in FIG. 2 cut along a plane including the axis CL2. In addition to the above-described conductive pin 210, the pressing and energizing portion 200 includes a guide portion 220, a first support portion 230, a first fixing screw 232, a second supporting portion 240, a second fixing screw 242, and a cap holder. 250, a cap 260, and an electrode member 270.

  The conductive pin 210 has a rod shape and is formed of a conductive material, such as a steel material (for example, stainless steel or S45C-H). The conductive pin 210 is located at the end on the rear end side, and has a flange portion 211 larger in diameter than the other portions and a tip end portion 212. The collar portion 211 is connected to the above-described conductive pin drive portion 405, and receives a driving force from the conductive pin drive portion 405. The distal end portion 212 applies a voltage to the assembly 100A in contact with the terminal fitting 40 of the assembly 100A in a test of withstand voltage described later.

  The guide portion 220 has a substantially cylindrical shape having an axial hole formed at a position intersecting the axis line CL2. The conductive pin 210 is accommodated in the axial hole of the guide portion 220. The guide portion 220 is formed of, for example, an insulating rubber, such as silicone rubber, acrylic rubber, or butyl rubber.

  The first support 230 has a disk shape and supports the guide 220. In the first support portion 230, a through hole penetrating in the thickness direction (axial direction) is formed at a position intersecting the axis line CL2. The through hole of the first support portion 230 communicates with the shaft hole of the guide portion 220. The first support portion 230 is fixed to the second support portion 240 by a first fixing screw 232 made of resin.

  The second support portion 240 has a substantially cylindrical shape having a flange portion on the rear end side. In the second support portion 240, an axial hole penetrating in the axial direction is formed at a position intersecting the axis line CL2. The second support portion 240 supports the first support portion 230 adjacent to the first support portion 230 on the tip side. The second support portion 240 is fixed to the surface on the tip end side of the movable shelf 450 by a metal second fixing screw 242. The first support portion 230 and the second support portion 240 are formed of a material having an insulating property, and in the present embodiment, a resin material such as polyacetal resin or polyether ether ketone resin.

  The electrode member 270 is fixed to the front end surface of the second support portion 240 by a metal electrode fixing screw 274. The electrode member 270 is formed of a conductive material, and contacts the metal shell 50 of the assembly 100A to ground the metal shell 50 in the inspection of the voltage resistance. The electrode member 270 has a disk shape in which a through hole in the thickness direction (axial direction) is formed in a portion intersecting the axis line CL2, and is formed of, for example, a low carbon steel material. The edge 272 of the inner circumferential surface forming the through hole of the electrode member 270 is chamfered.

  The cap holder 250 is accommodated and held in the axial hole of the second support portion 240. The cap holder 250 has a substantially cylindrical shape and is formed of an insulating material, in this embodiment, polyacetal. The cap holder 250 prevents the cap 260 from being deformed radially outward when the cap 260 is attached to the rear end side of the assembly 100A. Thereby, when the cap 260 is attached to the rear end side of the assembly 100A, the adhesion between the cap 260 and the surfaces of the insulator 10 and the terminal fitting 40 of the assembly 100A is improved.

  The cap 260 is accommodated and held in an axial hole formed at a position intersecting the axis CL 2 of the cap holder 250. The cap 260 is an insulating member having a substantially cylindrical shape. The cap 260 is made of an elastic and insulating rubber or elastomer, specifically, silicone rubber, acrylic rubber, or butyl rubber. The diameter of the shaft hole of the cap 260 is slightly smaller than the outer diameter of the insulator 10 (the outer diameter of the rear end side body portion 18) inserted into the shaft hole at the time of the voltage resistance inspection. For this reason, when the cap 260 is attached to the insulator 10, the inner circumferential surface of the cap 260 is in close contact with the surface of the insulator 10 at a predetermined pressure.

  As described above, the portion other than the conductive pin 210, the second fixing screw 242, the electrode member 270, and the electrode fixing screw 274 is formed of insulating rubber or resin as described above. This is to suppress the occurrence of a flashover phenomenon in which a current flows between the terminal fitting 40 and the metal shell 50 through the pressure applying unit 200 in the inspection of the voltage resistance of the insulator 10.

  As shown in FIG. 3, the conductive pin 210, the guide 220, the first support 230, the second support 240, the cap holder 250, the cap 260, and the electrode member 270 have an axis CL2 common to each other. The axial hole of the guide portion 220, the through hole of the first support portion 230, the axial hole of the cap 260, and the through hole of the electrode member 270 communicate with each other to form an insertion hole 290.

A-2-3. Detailed Configuration of Pressure Vessel 300 FIG. 4 is a perspective view of the pressure vessel 300 shown in FIG. The pressure vessel 300 includes an upper support portion 310, a seal portion 314, a seal portion presser 311, a tip end accommodating portion 320, a plurality of columns 321, a central support portion 330, and a lower support portion 340. ing. The upper support portion 310, the sealing portion 314, the sealing portion presser 311, the distal end accommodation portion 320, the central support portion 330, and the lower support portion 340 all have a cylindrical shape or a common axis line CL2. It is a cylindrical member.

  The upper support portion 310 is located on the most rear end side in the pressure vessel 300, and has a substantially cylindrical shape. A housing hole 312 is formed at a position intersecting the axis line CL2 of the upper support portion 310. The housing hole 312 is a through hole which penetrates the upper support portion 310 in the thickness direction (axial direction), and a part of the tip side of the assembly 100A, more specifically, the mounting screw portion in the inspection of voltage resistance. A portion corresponding to a part of the rear end side of 52 is accommodated. The diameter of the accommodation hole 312 is larger than the diameter of the thread of the attachment screw portion 52.

  A hole having a diameter larger than the diameter of the accommodation hole 312 is formed at the rear end of the accommodation hole 312 in the upper support portion 310, and the sealing portion 314 is accommodated in the hole. The sealing portion 314 has a ring shape in which an axial hole is formed, and the sealing portion 314 is accommodated in the hole provided in the upper support portion 310 so that its central axis coincides with the axis of the accommodation hole 312 . The axial hole of the sealing portion 314 has substantially the same diameter as the diameter of the accommodation hole 312 and is in communication with the accommodation hole 312. The axial hole of the sealing portion 314, like the accommodation hole 312, accommodates a part of the tip end side of the assembly 100A in the inspection of the voltage resistance. Hereinafter, a hole obtained by combining the axial hole of the sealing portion 314 and the housing hole 312 may be referred to as a housing hole 312. The sealing portion 314 seals the opening of the chamber 370 by coming into contact with the tip end surface 55 (FIG. 1) of the seat portion 54 of the assembly 100A in the inspection of the voltage resistance. The above-mentioned “opening of the chamber 370” is an opening sealed by the assembly 100A, and in the present embodiment, means the opening 317 at the upper end of the axial hole of the sealing portion 314. The sealing portion 314 is formed of, for example, a resin such as urethane or rubber.

  The sealing portion presser 311 has a substantially cylindrical shape thinner than the upper support portion 310. The outer diameter of the sealing portion presser 311 is substantially equal to the outer diameter of the upper support portion 310. Sealing part presser 311 is disposed in contact with the rear end side surface of upper support part 310 so that its central axis coincides with the central axis of upper support part 310. It is fixed. A through hole 313 is formed in the thickness direction at a position intersecting the axis line CL2 of the sealing portion presser 311. The diameter of the through hole 313 is larger than the diameter of the axial hole of the accommodation hole 312 and the sealing portion 314 and smaller than the outer diameter of the sealing portion 314. The through hole 313 communicates with the accommodation hole 312. The through hole 313 accommodates a part of the assembly 100A, more specifically, a part of the seat 54 in the inspection of voltage resistance. The sealing portion presser 311 holds the sealing portion 314 from the rear end side, and limits the movement of the sealing portion 314 in the axial direction.

  The tip storage portion 320 has a cylindrical shape, and is adjacent to the top support portion 310 on the tip side. The tip storage portion 320 is formed of, for example, a transparent resin material such as an acrylic resin. A space inside the tip storage portion 320 is in communication with the storage hole 312. The tip storage portion 320 is a tip portion of the assembly 100A, more specifically, a portion corresponding to a portion on the tip side of the mounting screw portion 52 in the inspection of voltage resistance described later, and a tip portion more than the portion The portion located on the side (the center electrode 20, a part of the leg 13 and the ground electrode 30) is accommodated. The outer diameter of the distal end accommodating portion 320 is smaller than the outer diameter of the upper support portion 310.

  The plurality of columns 321 are arranged at predetermined intervals in the circumferential direction on the radially outer side of the distal end accommodating portion 320. The support column 321 is a thin cylindrical member, one end of which is connected to the end surface of the upper support portion 310 and the other end of which is connected to the end surface of the central support portion 330.

  The central support portion 330 has a substantially cylindrical shape, and is disposed adjacent to the tip end portion 320 on the tip end side. The outer diameter of the central support 330 is approximately equal to the outer diameter of the upper support 310. The central support portion 330 is disposed in contact with the distal end accommodating portion 320 and is connected to the pipe 360. The central support 330 includes a main support 331 and a visible portion 332.

  A central hole 335 penetrating in the axial direction is formed in the main support portion 331 at a position intersecting the axis line CL2. The main support portion 331 is formed with a communication hole 333 communicating the connection portion of the pipe 360 with the central hole 335. The visible portion 332 is a disk-shaped member disposed in contact with the surface on the tip end side of the main support portion 331. The front end side surface of the visible portion 332 and the rear end side surface of the main support portion 331 are joined. The visible portion 332 is formed of a transparent material such as acrylic resin or glass.

  The housing hole 312, the inner space of the tip housing portion 320, and the central hole 335 are in axial communication with each other, and the above-described chamber 370 is formed inside the pressure vessel 300. The visible portion 332 covers the distal end side of the central hole 335 described above, and forms the bottom 380 of the chamber 370. A pressure control valve (not shown) is connected to the pipe 360, and compressed air is supplied into the chamber 370 through the pipe 360, whereby the pressure in the chamber 370 is boosted. In the voltage resistance test, the chamber 370 contains only a part of the tip side of the assembly 100A. For this reason, the size of the pressure vessel 300 is smaller than that of a vessel having a chamber for accommodating the entire assembly 100A.

  The lower support portion 340 has a substantially cylindrical shape, and is disposed adjacent to the central support portion 330 on the distal end side. In the lower support portion 340, an observation hole 345 penetrating in the axial direction is formed at a position intersecting the axis line CL2. From the tip side of the lower support portion 340, the inside of the chamber 370 can be observed through the observation hole 345 and the visible portion 332 (bottom portion 380). The surface on the rear end side of the lower support portion 340 is joined to the surface on the tip end side of the central support portion 330 (the surface on the tip end side of the visible portion 332). The outer diameter of the lower support 340 is larger than the outer diameter of the central support 330. The lower support portion 340 is fixed to the lower fixing plate 410 by a plurality of fixing screws 342.

A-2-4. Process of Manufacturing Method of Spark Plug 100 FIG. 5 is a flowchart showing the process of the manufacturing method of spark plug 100. In S10 to S25, the aforementioned assembly 100A is prepared. First, in S10, respective members constituting the spark plug 100 are prepared. In S15, the center electrode 20 and the terminal fitting 40 are inserted into the axial hole 12 of the insulator 10, and the center electrode 20 and the terminal fitting 40 are assembled to the insulator 10. At this time, the seal members 60 and 80 and the resistor 70 of FIG. 1 are enclosed between the shaft hole 12 and the terminal fitting 40 in the shaft hole 12. In S20, the ground electrode 30 is joined to the front end surface of the metal shell 50 by, for example, resistance welding. In S25, the insulator 10 in which the center electrode 20, the terminal fitting 40 and the like are assembled in S15, and the metal shell 50 are assembled to obtain an assembly 100A.

  FIG. 6 is an explanatory view of a method of manufacturing the spark plug 100. As shown in FIG. The assembly 100A is shown by FIG. 6 (A). As described above, the difference between the assembly 100A and the spark plug 100 is only that the ground electrode 30 is not bent and the gasket 5 is not assembled in the assembly 100A.

  In S30, a lubricant is attached to the surface of the insulator 10, specifically, to the surface of the rear end side body portion 18 of the insulator 10 exposed to the rear end side of the metal shell 50. In the present embodiment, a powder of talc (talc) is used as the lubricant. If the particle size of talc powder TK is excessively large, the adhesion between the insulator 10 and the cap 260 may decrease when the cap 260 is attached to the insulator 10 in S60 described later, The particle size of talc powder TK is preferably, for example, 850 μm or less. In the present embodiment, the particle size of talc powder TK is adjusted to 5 μm to 850 μm. An axial range CA to which the lubricant is attached is a portion covered by a cap 260 attached in S40 described later, and is exposed from the metal shell 50 of the rear end side body portion 18 as shown in FIG. Part of the

  FIG. 6 (B) shows a description of the lubricant deposition step of depositing the lubricant. In the lubricant attachment step of the present embodiment, the lubricant is attached to the surface of the insulator 10 by bringing the object to which the lubricant is attached into contact with the surface of the insulator 10. Specifically, as shown in FIG. 6 (B), a cloth bag 600 containing talc powder TK is prepared. The gaps (openings) between the fibers of the bag 600 are made larger than the particle size of talc powder TK. Therefore, for example, when an impact is applied to the bag 600, some talc powder TK is released to the outside from the interstices between the fibers, and adheres and stays on the surface of the bag 600 and in the vicinity thereof. By bringing the bag 600 in this state into contact with the surface of the insulator 10, talc powder can be deposited on the surface of the insulator 10. For example, the assembly 100A is attached to a grip (not shown) and rotated about its axis by the power of the motor as indicated by an arrow AR2. The bag 600 held by another grasping tool (not shown) is reciprocated in the radial direction of the assembly 100A multiple times as indicated by the arrow AR1. As a result, the bag 600 collides with and contacts with the rear end side body 18 of the rotating assembly 100A multiple times. As a result, talc powder TK adheres over the entire circumference of the above-described axial range CA of the rear end side body portion 18 of the assembly 100A.

  In S35, the front end side of the assembly 100A is inserted into the pressure vessel 300 from the upper end of the through hole 313 of the sealing portion presser 311. As a result, the assembly on the tip end side of the assembly 100A (specifically, the portion on the tip end side of the seat 54 of the metal shell 50) is positioned inside the pressure vessel (that is, inside the chamber 370). The solid 100A is attached to the pressure vessel 300. The state of the inspection apparatus 500 and the assembly 100A immediately after S35 is performed is as shown in FIG. That is, the assembly 100A is attached to the pressure vessel 300, and the pressing and energizing unit 200 is disposed on the rear end side of the assembly 100A. When S35 is performed, the opening of the chamber 370, that is, the opening 317 of the sealing portion 314 is closed by the seat portion 54 of the assembly 100A, but at this point, the airtightness inside the chamber 370 is secured. Absent.

  In S40, the pressing / energizing unit 200 is moved (lowered) in the tip direction FD. The cap 260 is thereby attached to the assembly 100A. Further, since the force in the distal direction FD is applied to the assembly 100A by the conductive pin 210 and the electrode member 270, the front end surface 55 of the seat portion 54 of the assembly 100A is pressed against the upper end surface of the sealing portion 314. The opening 317 of the pressure vessel 300 is sealed by the assembly 100A.

  FIG. 7 is an explanatory view showing the inspection apparatus 500 and the assembly 100A in a state where S40 is performed. In FIG. 7, for convenience of explanation, only the pressure applying unit 200 and the pressure vessel 300 in the inspection apparatus 500 are shown. As shown in FIG. 7, S40 is performed in a state where the axis CL2 of the inspection apparatus 500 and the axis CL1 of the assembly 100A coincide with each other.

  When the pressing unit 200 moves in the front end direction FD from the state shown in FIG. 1, the rear end side of the assembly 100A is inserted into the insertion hole 290 of the pressing unit 200. When the movement further progresses, the rear end side body 18 of the insulator 10 is inserted into the axial hole of the cap 260. Thus, the cap 260 is attached to the assembly 100A so as to cover the surface of the portion of the assembly 100A exposed to the rear end side of the metal shell 50. Although the inner diameter of the shaft hole of the cap 260 is smaller than the outer diameter of the rear end side body portion 18, since the cap 260 is formed of an elastic material (for example, rubber), the diameter of the shaft hole of the cap 260 is increased. The end body 18 is inserted. The diameter expansion of the outer diameter of the cap 260 is limited by the cap holder 250. For this reason, in the state shown in FIG. 6, the inner circumferential surface forming the axial hole of the cap 260 contacts the outer circumferential surface of the rear end side body portion 18 with relatively strong pressure. As a result, the adhesion between the cap 260 and the rear end side body portion 18 is improved. Similarly, the cap 260 also adheres to the cap mounting portion 41 of the terminal fitting 40. As shown in FIG. 7, the axial length of the cap 260 is the entire axial length of the portion of the insulator 10 exposed at the rear end and the axis of the cap mounting portion 41 of the terminal fitting 40. Longer than the sum of the direction length. The cap 260 is in close contact with substantially the entire outer peripheral surface of the portion of the insulator 10 exposed at the rear end and substantially the entire outer peripheral surface of the cap mounting portion 41.

  As shown in FIG. 7, the pressing / energizing portion 200 moves to a position where the edge 272 of the electrode member 270 contacts the rear end side of the tool engaging portion 51 of the assembly 100A. Then, even after the electrode member 270 comes in contact with the tool engaging portion 51, the pressing and energizing portion 200 is assembled via the electrode member 270 until the pressing and energizing portion 200 is moved in the rear end direction BD in S60 described later. The solid 100A is continuously pressed in the tip direction FD. The pressing force at this time is a force that can withstand pressure increase up to a predetermined pressure (for example, 5 MPa) in the chamber 370, and is, for example, a force of 300 kg.

  As described above, since the opening 317 of the chamber 370 is sealed by pressing the pressure vessel 300 (sealing portion 314) by the assembly 100A, the airtightness of the pressure vessel 300 can be easily ensured.

  Further, in a state where the axis CL2 of the opening 317 of the chamber 370 and the axis CL1 of the assembly 100A coincide with each other, pressing of the assembly 100A by the pressing and energizing unit 200 and attachment of the cap 260 to the insulator 10 are To be done. For this reason, since it can suppress that the opening 317 is shifted and closed by the assembly 100A, the airtightness of the pressure vessel 300 can be improved. Further, since the cap 260 can be suppressed from being attached to the insulator 10 in a shifted manner, the occurrence of the flashover phenomenon in which current flows along the surface of the portion exposed to the rear end side of the insulator 10 can be suppressed.

  Further, since the pressing axis (axis line CL1) at the time of pressing the assembly 100A coincides with the central axis (axis line CL2) of the opening 317 to be sealed, the pressing axis and the central axis of the opening 317 The rigidity of the pressure applying unit 200 can be reduced in the case of obtaining the same air tightness as compared with the configuration in which the gap is shifted. For this reason, many components of the pressure applying unit 200 can be formed of insulating rubber or resin material. As a result, it is possible to more effectively suppress the occurrence of the above-described flashover phenomenon, and to realize the downsizing and weight reduction of the pressure applying unit 200.

  In S45, a pressure control valve (not shown) is controlled to supply air into the chamber 370 to pressurize the inside of the chamber 370 and pressurize it to a predetermined pressure (for example, 5 MPa). Since only the portion of the assembly 100A on the distal side of the seat portion 54 is accommodated inside the chamber 370, the volume of the chamber 370 is smaller than that of the configuration that accommodates the entire assembly 100A. Therefore, boosting in the chamber 370 is completed in a short time.

  In S50, with the pressure in the chamber 370 raised to a predetermined pressure, a predetermined voltage is applied to the assembly 100A, and the tip of the assembly 100A is imaged using an imaging device (not shown). Specifically, 30 to 45 kV (between the terminal fitting 40 (and the center electrode 20 electrically connected to the terminal fitting 40) and the metal shell 50 through the conductive pin 210 and the electrode member 270. A relatively high voltage of kilovolts is applied several times (for example, several hundred times). Then, each time a voltage is applied, imaging of the tip of the assembly 100A is performed. When defects such as pinholes do not occur in the insulator 10, spark discharge does not occur because the center electrode 20 and the ground electrode 30 are far apart from each other than the spark discharge gap. On the other hand, when the insulator 10 has a defect, a spark is generated through the defect, so that a spark appears in the captured image of the tip of the assembly 100A. At this time, since the cap 260 formed of the insulating material is in close contact with the rear end side of the insulator 10, the terminal fitting 40 and the metal shell along the surface of the portion exposed to the rear end side of the insulator 10 The occurrence of a so-called flashover phenomenon in which a current flows between 50 and 50 is suppressed. Even if such a flashover phenomenon occurs, spark discharge does not occur on the tip side of the assembly 100A. When the flashover phenomenon occurs, a short circuit occurs between the terminal fitting 40 and the metal shell 50, so a predetermined voltage can not be applied between the terminal fitting 40 and the metal shell 50. For this reason, if the flashover phenomenon occurs, the withstand voltage of the insulator 10 can not be properly inspected.

  In S55, the pressure in the chamber 370 is reduced to atmospheric pressure by controlling a pressure control valve (not shown).

  In S60, the slide support portion 440 is driven, and the pressing and energizing portion 200 is moved in the rear end direction BD by a predetermined distance. At this time, the conductive pin drive unit 405 controls the conductive pin 210 so that the absolute position of the conductive pin 210 in the axial direction does not change. Specifically, as the absolute position of the axial direction of the pressing / energizing unit 200 is moved in the rear end direction BD by the slide support portion 440 moving in the rear end direction BD, the conductive pin drive portion 405 is a conductive pin 210 is moved in the tip direction FD with respect to the other portion of the pressure applying unit 200.

  FIG. 8 is an explanatory view showing the inspection apparatus 500 and the assembly 100A in a state in which S60 is being performed. As shown in FIG. 8, when S60 is executed, the pressing unit 200 moves in the rear end direction BD while the terminal fitting 40 is pressed in the front end direction FD by the conductive pin 210. By such an operation, the cap 260 moves in the distal direction FD relative to the insulator 10 together with the pressing and energizing unit 200 while the axial position of the assembly 100A (insulator 10) remains unchanged. For this reason, the cap 260 is removed from the insulator 10. The powder TK of talc as a lubricant adheres to the portion (the surface of the rear end side body portion 18) of the insulator 10 which is covered by the cap 260 (see S30). For this reason, the frictional force generated between the cap 260 and the assembly 100A when the cap 260 is moved relative to the assembly 100A is reduced compared to the case where the lubricant is not attached. There is. To this end, the cap 260 is easily removed from the assembly 100A.

  In S60, after the cap 260 is removed, the pressing / energizing unit 200 further moves in the tip direction FD and returns to the position shown in FIG. In S65, the conductive pin drive unit 405 moves the conductive pin 210 in the rear end direction BD with respect to the pressing / energizing unit 200. As a result, the inspection apparatus 500 returns to the state of FIG.

  In S70, the voltage resistance of the assembly 100A is evaluated based on the captured image obtained in S50. For example, in the plurality of captured images obtained in S50, the withstand voltage is evaluated as pass when the number of images in which the spark discharge is not reflected is equal to or more than the threshold, and the withstand voltage is less than the threshold. Voltage potential is rated as a failure. Such a threshold is determined experimentally by performing evaluation using, for example, the assembly 100A in which the defective insulator 10 is assembled.

  In S75, bending processing is performed on the ground electrode 30 of the assembly 100A that has passed the voltage resistance. For example, as shown in FIG. 1, the ground electrode 30 is bent so that the tip end face of the center electrode 20 (center electrode tip 29) faces one side face of the tip end of the ground electrode 30. At this time, the air gap between the tip end surface of the center electrode 20 and the ground electrode 30 is a spark gap in which a spark discharge is generated, and is set to a predetermined dimension.

  As described above, since the bending process of the ground electrode 30 is performed after the voltage resistance inspection, the distance between the ground electrode 30 and the center electrode 20 can be made relatively large in the voltage resistance inspection. Therefore, a relatively high voltage can be applied in the inspection of the voltage resistance.

  In S80, the gasket 5 is attached to the front end side of the seat 54 as shown in FIG. As described above, since the gasket 5 is attached after the voltage resistance inspection, damage to the gasket 5 can be suppressed when the assembly 100A adheres to the pressure vessel 300 in the voltage resistance inspection. Through the above steps, the spark plug 100 is completed.

  According to the embodiment described above, before attaching the cylindrical cap 260 so as to cover the surface of the portion of the insulator 10 exposed to the rear end (that is, before S40), the lubricant of S30 In the attaching step, a lubricant is attached to the surface of the insulator 10 covered by the cap 260. As a result, even if the cap 260 is strongly adhered to the insulator 10 at the time of inspection, it becomes easy to remove the cap 260 from the assembly 100A at S60 after the application of the predetermined voltage at S50. Therefore, when inspecting the insulator 10 of the spark plug 100, the inspection can proceed smoothly while suppressing the flashover phenomenon.

  For example, when the cap 260 is not firmly attached to the insulator 10 at the time of inspection, it is easy to remove the cap 260 from the assembly 100A, but the flashover phenomenon occurs when a predetermined voltage is applied in S50. It may be easier to do and inspection may not be performed properly. Alternatively, it may be necessary to lower the predetermined voltage applied in S50, which may make it impossible to perform a more stringent voltage resistance test. On the other hand, in the case where the cap 260 is strongly adhered to the insulator 10 at the time of inspection without adhering a lubricant at S30, although the predetermined voltage applied at S50 can be increased, from the assembly 100A It becomes difficult to remove the cap 260. For example, in S60, the conductive pin drive portion 405 can not move the conductive pin 210 in the tip direction FD with respect to the other portion of the pressing and energizing portion 200, and the cap 260 can not be removed from the assembly 100A. . In this case, when the pressure applying unit 200 is moved in the rear end direction BD, the assembly 100A is not separated from the cap 260 and the pressure applying unit 200, and remains attached to the pressure applying unit 200. Then, after S60, it is necessary for the operator to remove the assembly 100A from the pressure applying unit 200 and the cap 260, and the smooth progress of inspection and manufacture of the spark plug 100 is hindered. In addition, if it is attempted to remove the cap 260 forcibly, the inner surface of the cap 260 is degraded and the surface is roughened, so that the flashover phenomenon is likely to occur. According to the present embodiment, the occurrence of such a defect can be suppressed.

  Furthermore, the lubricant used in the lubricant deposition step of S30 is talc powder TK. Even if a small amount of talc powder adheres to the insulator, the performance and appearance of the spark plug 100 are hardly affected. Since talc powder is used as the lubricant for this purpose, the talc powder removal process can be omitted or simplified. Also, since talc is insulating, it does not cause a flashover phenomenon at the time of inspection.

  Furthermore, since the lubricant attachment step of S30 is a step of bringing the object to which the lubricant is attached into contact with the surface of the insulator 10, the lubricant can be easily attached to the surface of the insulator 10.

  More specifically, as shown in FIG. 6 (B), a cloth-made bag 600 for containing a lubricant powder (in this embodiment, a talc powder TK) as an object to which lubricant is attached. Therefore, a powdery lubricant can be easily attached to the surface of the insulator 10.

  Furthermore, in the present embodiment, with the cap 260 attached to the insulator 10 at S40, the inner circumferential surface of the cap 260 is substantially the outer circumferential surface of the portion of the insulator 10 exposed at the rear end. It is in close contact with the whole and almost the whole of the outer peripheral surface of the cap mounting portion 41. As described above, since the cap 260 is closely attached to a wide range of the rear end side body portion 18 and the terminal fitting 40, for example, as compared with the case of using a cap that covers only a narrower portion of the surface of the insulator 10, The voltage that can be applied can be increased at S50. As the cap 260 closely adheres to such a wide range, removal of the cap 260 may be difficult. However, in the present embodiment, as described above, a lubricant is applied to the surface of the portion covered by the cap 260 in S30. As it adheres, removal of the cap 260 can be facilitated.

  Furthermore, in the present embodiment, only a part of the tip side of the assembly 100A is accommodated in the chamber 370, so that the assembly 100A can be attached to and removed from the pressure vessel 300 in a short time. In addition, since the volume of the chamber 370 can be reduced, pressure increase and decrease in the chamber 370 can be performed in a short time. Therefore, it is possible to shorten the time required for the inspection of the voltage resistance, and hence, the time required for manufacturing the spark plug 100. Further, since the volume of the chamber 370 can be reduced, the pressure vessel 300 can be miniaturized.

  Furthermore, since the opening 317 of the chamber 370 is sealed using the assembly 100A, the mounting of the assembly 100A to the pressure vessel 300 and the sealing of the opening 317 of the chamber 370 are performed as separate steps. Man-hours can be reduced.

  Furthermore, since the conductive pin 210 is movably disposed in the insertion hole 290 of the pressing unit 200, the pressing unit 200 is moved in the tip direction FD and the pressing unit 200 presses the assembly 100A. The conductive pin 210 can be in contact with the terminal fitting 40 of the assembly 100A. Therefore, the number of man-hours can be reduced as compared with a configuration in which the pressing of the assembly 100A by the pressing and energizing unit 200 and the contact of the conductive pin 210 with the terminal fitting 40 are performed as separate steps. Similarly, since the electrode member 270 is disposed at the tip of the pressing part 200, the pressing part 200 is moved in the tip direction FD, and the assembly 100A is pressed by the pressing part 200. The electrode member 270 can be in contact. Therefore, the number of man-hours can be reduced compared to the configuration in which the process of pressing the assembly 100A by the pressing and energizing unit 200 and the process of contacting the electrode member 270 with the metal shell 50 and grounding the metal shell 50 are performed as separate processes. be able to.

B. Modification (1) In the above embodiment, the lubricant is attached to the surface of the insulator 10 in the lubricant attachment step of S30. Instead of this, the lubricant attachment step of S30B indicated by a broken line in FIG. 5 may be performed. In S30B of FIG. 5, the inner surface IS of the cap 260 of the pressing / energizing portion 200 of FIG. 3, that is, the inner surface IS covering the surface of the insulator 10 when the cap 260 is attached to the assembly 100A in S40. Adhere the material. In this case, for example, a cotton swab to which a powder TK of talc as a lubricant adheres is adhered to the inner surface IS by bringing the swab into contact with the inner surface IS of the cap 260. The adhesion of the lubricant may be performed manually by an operator or automatically by a robot. Also, the adhesion of the lubricant may be performed automatically, for example, by spraying the lubricant in liquid or powder form on the inner surface IS of the cap 260 using a sprayer or a duster.

  Note that both the lubricant attachment step of S30 of the above embodiment and the lubricant attachment step of S30B of the present modification may be performed. That is, a lubricant may be attached to both the surface of the insulator 10 and the inner surface IS of the cap 260 before S40 of FIG.

(2) In the above embodiment, at S40, the cap 260 is attached to the assembly 100A so as to cover the entire portion of the insulator 10 exposed to the rear end side of the metal shell 50. Instead of this, for example, a portion of the insulator 10 exposed to the rear end side from the metal shell 50 (for example, a part on the front end side, a part on the rear end side) is covered, for example, A cap having a shorter axial length than the cap 260 of the embodiment may be used.

  Further, the shape and dimensions of the cap 260 can be variously changed. For example, instead of omitting the cap holder 250, a cap having a shape in which the cap holder 250 and the cap 260 of this embodiment are integrated is adopted. It may be done. In general, the cap is preferably an insulating member including a cylindrical portion into which the insulator 10 is inserted.

(3) In the above-described embodiment, in the lubricant adhering step of S30, the lubricant is adhered to the whole of the portion of the insulator 10 exposed to the rear end side of the metal shell 50. Instead of this, the lubricant may be attached only to a part of the portion exposed to the rear end side. In general, it is preferable to attach a lubricant to all or part of the surface of the insulator 10 covered by the cap 260. Also, in addition to the surface of the insulator 10, a lubricant may be attached to the terminal fitting 40.

(4) In the said embodiment, although the powder TK of talc is employ | adopted as a lubricating material, another substance may be employ | adopted as a lubricating material. For example, powder of a compound containing silicon or powder of a resin may be used as the lubricant. Further, as the lubricant, a substance different from the powder, for example, a liquid or gel-like insulating substance such as an insulating oil may be used.

(5) Depending on the type and amount of lubricant used, for example, a step of removing the lubricant from the surface of the insulator 10 or the terminal fitting 40 at any timing after S60, for example, the insulator 10 or the terminal fitting 40 The process of wiping off the lubricant from the surface of may be performed.

(6) In the lubricant adhering step of S30, the lubricant is adhered by bringing the bag 600 into contact with the surface of the insulator 10. Alternatively, the lubricant may be attached by attaching the lubricant to another object (for example, a porous body such as a sponge) and bringing the object into contact with the surface of the insulator 10.

(7) The lubricant attachment step of S30 may be variously modified depending on the type of lubricant and the like. For example, when talc powder is used as in the present embodiment, for example, a process of rubbing an object obtained by solidifying talc powder onto the surface of the insulator 10 may be employed. In this case, an object obtained by solidifying talc powder is annularly formed, and in a state in which the insulator 10 is inserted in the hole of the annular object, a process of rubbing the annular object on the surface of the insulator 10 is employed. It may be done. When a liquid or gel-like lubricant is used, for example, the lubricant stored in the container may be a part of the rear end side of the assembly 100A (a part of the rear end side of the insulator 10) A dipping step may be employed.

(8) In the said embodiment, although the part accommodated in the chamber 370 among the assembly 100A was a tip side rather than the seat part 54, it is not restricted to this. At least a part of the tip side of the assembly 100A, in particular, the air gap 31 (FIG. 1) formed between the inner peripheral surface of the axial hole of the metal shell 50 and the outer peripheral surface of the leg length 13 of the insulator 10 Preferably, the portion is housed within the chamber 370.

(9) In the above-described embodiment, in order to remove the cap 260 from the insulator 10 in S60, the conductive pin 210 is moved relative to the pressing and energizing unit 200 while moving the pressing and energizing unit 200 in the rear end direction BD by a predetermined distance. Relative to the distal direction FD. Alternatively, the pressure vessel 300 and the lower fixing plate 410 can be moved in the axial direction, and the assembly 100A and the pressure vessel 300 can be engaged with each other. The cap 260 may be removed from the insulator 10 by moving in the direction FD.

(10) In the above embodiment, the bending step (S75) of the ground electrode 30 and the assembling step (S80) of the gasket 5 are both performed after the voltage resistance inspection (S35 to S70). It may be performed before the sex check.

(11) In the above embodiment, the lubricant adhesion step of S30 is performed on the insulator 10 of the assembly 100A after the assembly 100A is prepared in S10 to S25. Instead of this, the lubricant attachment process may be performed while the assembly 100A is prepared at S10 to S25. For example, the lubricant adhesion process may be performed on the insulator 10 before being assembled with the metal shell 50 or the insulator 10 before the center electrode 20 and the terminal metal fitting 40 are assembled. Moreover, a lubricant attachment process may be performed with respect to the insulator 10 of the state attached to the pressure vessel 300 in S35. Generally, the lubricant attachment process may be performed before the cap 260 is attached to the insulator 10 at S40.

(12) In the above embodiment, the voltage applied in step S50 is a voltage that does not cause spark discharge on the tip side of the assembly 100A. Instead of this, a voltage high enough to generate spark discharge may be applied. In this case, in a normal state, a flashover phenomenon occurs along the surface of the leg 13 and a spark is generated on the tip surface of the insulator 10 (leg 13). Therefore, when the spark which arose in this part in a photography picture is checked, it can be judged that it is normal. On the other hand, if a through hole is generated in the insulator 10 due to a defect such as a pinhole, a discharge is generated through the through hole, so a spark is generated on the tip end surface of the insulator 10 (leg length 13). Does not occur. Therefore, it is determined that the voltage resistance is a failure, that is, that the insulator 10 has a defect when no spark is confirmed in such a portion in the photographed image.

(13) The configuration of the inspection apparatus 500 in the above embodiment is merely an example and can be variously changed. For example, although the tip storage portion 320 of the pressure vessel 300 is transparent and the inside is visible, the inside may not be visible. Similarly, the visible portion 332 may not be visible. In addition, the upper support 310, the central support 330, and the lower support 340 may be formed of a transparent material so that the entire chamber 370 can be viewed from the outside. Further, the inspection apparatus 500 may be configured to be turned upside down. In this configuration, for example, first, the rear end side of the assembly 100A is inserted into the insertion hole 290 of the pressure applying unit 200, and the cap 260 is attached to the assembly 100A. Thereafter, the pressure applying unit 200 to which the assembly 100A is attached is raised, and the assembly 100A is inserted into the chamber 370 of the pressure vessel 300.

  As mentioned above, although this invention was demonstrated based on embodiment and a modification, above-mentioned embodiment of the invention is for making an understanding of this invention easy, and does not limit this invention. The present invention can be modified and improved without departing from the spirit and the scope of the claims, and the present invention includes the equivalents thereof.

  Reference Signs List 5 gasket, 6 ring member, 8 plate packing, 9 talc, 10 insulator, 12 axial hole, 13 leg length, 15. 1st reduced outer diameter portion 17 17 tip side body portion 18 rear end side body portion 19 collar portion 20 center electrode 25 center electrode body 29 ... center electrode tip, 30 ... ground electrode, 31 ... air gap, 40 ... terminal fitting, 41 ... cap mounting portion, 42 ... ridge portion, 43 ... leg portion, 50 ... Main metal fitting, 51 ... Tool engagement portion, 52 ... Mounting screw portion, 53 ... Crimping portion, 54 ... Seat portion, 56 ... Shelf portion, 58 ... Compression Deformed part, 59: through hole, 60: seal member, 70: resistor, 80: seal member, 100: spark plug, 100A: assembly, 200: pressing Electric conduction part, 210 ... conductive pin, 211 ... collar part, 212 ... tip part, 220 ... guide part, 230 ... first support part, 232 ... first fixing screw, 240 ... 2nd Holding part, 242: second fixing screw, 250: cap holder, 260: cap, 270: electrode member, 272: edge, 274: electrode fixing screw, 290: Insertion hole, 300, pressure vessel, 310, upper support portion, 311, sealing portion presser, 312, accommodation hole, 313, through hole, 314, sealing portion, 316 ... fixed screw, 317 ... opening, 320 ... tip accommodation section, 321 ... post, 330 ... central support section 331 ... main support section 332 ... visible section, 333 ... communication hole, 335 ... central hole, 340 ... lower support portion, 342 ... fixing screw, 345 ... observation hole, 360 ... piping, 370 ... chamber, 380 ... Bottom portion 400 Voltage application portion 405 Conductive pin drive portion 410 Lower fixing plate 412 Through hole 420 Upper fixing plate 430 Strut 440 ... slide support, 450 ... moving shelf, 500 ...査 device, 600 ... bags, FD ... distal direction, BD ... rear direction, TK ... talc powder

Claims (5)

A method of manufacturing a spark plug including an insulator inspection step, the method comprising:
The inspection process of the insulator is
(A) A cylindrical metal shell having a through hole extending in the axial direction, and a part thereof is held in the through hole, the rear end is exposed to the rear end side from the metal shell, and extends along the axial direction An insulator having an axial hole, a center electrode whose rear end is located in the axial hole, and a front end located on the rear end side of the central electrode in the axial hole from the rear end, the rear end is more than the insulator Preparing an assembly comprising a terminal fitting exposed on the rear end side and a ground electrode joined to the metal shell;
(B) attaching the assembly to the pressure vessel such that a portion on the tip side of the assembly is located inside the pressure vessel;
(C) attaching an insulating member including a cylindrical portion to the assembly so as to cover the surface of at least a portion of the portion of the insulator exposed to the rear end side of the metal shell;
(D) pressurizing the inside of the pressure vessel and applying a predetermined voltage between the terminal fitting and the metal shell;
(E) removing the insulating member from the assembly after application of the predetermined voltage;
Equipped with
Before the step (c), at least the insulation of the surface of the insulator covered by the insulating member attached in the step (c) and the inner surface of the insulating member covering the surface of the insulator A method for manufacturing a spark plug, comprising a lubricant adhesion step of adhering lubricant to a surface of a body . A method of manufacturing a spark plug according to claim 1 , wherein
The lubricant attachment step is a step of bringing an object to which the lubricant is attached into contact with at least the surface of the insulator of the surface of the insulator and the inner surface of the insulating member. Method. A method of manufacturing a spark plug including an insulator inspection step, comprising:
The inspection process of the insulator is
(A) A cylindrical metal shell having a through hole extending in the axial direction, and a part thereof is held in the through hole, the rear end is exposed to the rear end side from the metal shell, and extends along the axial direction An insulator having an axial hole, a center electrode whose rear end is located in the axial hole, and a front end located on the rear end side of the central electrode in the axial hole from the rear end, the rear end is more than the insulator Preparing an assembly comprising a terminal fitting exposed on the rear end side and a ground electrode joined to the metal shell;
(B) attaching the assembly to the pressure vessel such that a portion on the tip side of the assembly is located inside the pressure vessel;
(C) attaching an insulating member including a cylindrical portion to the assembly so as to cover the surface of at least a portion of the portion of the insulator exposed to the rear end side of the metal shell;
(D) pressurizing the inside of the pressure vessel and applying a predetermined voltage between the terminal fitting and the metal shell;
(E) removing the insulating member from the assembly after application of the predetermined voltage;
Equipped with
Wherein prior to step (c), the inner surface of said insulating member covering a surface of the pre-Symbol insulator, comprising a lubricating material adhering step of adhering the lubricant,
The lubricating material applying step, said object skids is attached, and wherein the step der Rukoto contacting the inner surface of the insulating member, the manufacturing method of the spark plug. A method of manufacturing a spark plug according to claim 2 , wherein
The method for manufacturing a spark plug, wherein the object to which the lubricant adheres is a cloth bag containing the powder of the lubricant.
A method of manufacturing a spark plug according to any one of claims 1 to 4 , wherein
The method for manufacturing a spark plug, wherein the lubricant is talc powder.

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